1. Field of the Invention
The present invention relates to an endoscope, and more particularly to an endoscope system including two endoscopes that are different from each other in viewing angle.
2. Description of the Related Art
Conventionally, an endoscope has been widely used in a medical field and the like. The endoscope is employed to observe organs and the like inside a body cavity by inserting an elongate insertion portion into the body cavity, and to operate various treatments by using a treatment instrument that is inserted into a treatment instrument insertion channel, if necessary. A bendable portion is provided at a distal end of the insertion portion, and an observation direction of an observation window of the distal end portion is changed by manipulating a manipulating portion of the endoscope.
A viewing angle of the conventional endoscope is, for example, 140° (degree), and an operator observes inside the body cavity by an observation image corresponding to the viewing angle. When the operator desires to observe a region outside a region corresponding to a field of view during the observation inside the body cavity, the operator can bend the bendable portion to observe such region.
On the other hand, an endoscope having a wider viewing angle has been proposed to allow an observation of a wider region. The endoscope has an advantage that the observation is easily performed and a region necessary to be treated is easily found since an imaging region is widened by having the wide viewing angle (for example, see Japanese Patent Application Laid-Open No. H4-102432).